Filter blank



M y 6,1944. v J. M. SANFORD 2,349,115

FILTER BLANK Filed Aug. 11, 1942 INVENTOR- Patented May 16, 1944 UNITEDSTATES PATENT OFFICE FILTER BLANK John M. Sanford, Terre Haute, Ind.

Application August 11, 1942, Serial No. 454,443

1 Claim.

This invention relates to filter blanks of the type employed forlaboratory purposes.

Conventiona1 filters employed for laboratory purposes usually comprise afunnel-shaped support having an angle of about sixty degrees coactingwith a paper filter blank, circular in contour. This paper blank isfolded and fitted into the funnel to be supported thereby. Such filterdevices require considerable filter paper.

Accordingly, an object of my invention is to provide a filter sodesigned as to coact with the usual funnel-shaped support but in whichthe filter blank is so contoured as to require considerably lessmaterial to effect a considerable savin in filter paper or othermaterial used for such purposes.

In the accompanying drawing:

Figure 1 is a plan view of a blank in accordance with my invention andillustrating the manner in which the blanks are cut to effect saving inthe filtering material from which the blank is cut;

Figure 2 is a view illustrating the first step in folding the blank ofFigure 1;

Figure 3 illustrates the second folding step;

Figure 4 illustrates the blank folded for insertion in the funnel;

Figure 5 is a plan view of a different form of blank;

Figure 6 illustrates the first step in folding the blank of Figure 5;

Figure '1 illustrates the second folding step; and

Figure 8 illustrates the filter blank folded for insertion in thefunnel.

Figure 1 illustrates a filter blank l0 cut concentrically about thecenter l2 but in which the blank is provided with a concaved edge l4defining the line of separation between the blank 10 and the next blankit cut from the filter stock. Thus the edge It conforms in contour tothe curvature l8 of the filter blank Ill. The line of severance islocated some distance short of the center l2 so that the width of theblank H] at the line 20 passing through the center I2 is slightly widerthan the radius of the blank to provide a flap 22 extending up to theline 24 passing through the center l2 and at right angles to the line20.

In folding the blank In, the blank is first folded back upon itselfalong the line 20, as in Figure 2, and the flap or flange 22 is thenfolded back upon the blank along the line 24, as in Figure 3. The blankis then opened to the contour of Figure 4 for insertion in the funnel.Figure 4 illustrates the flap 22 as lying double against the outer faceof the blank Ill so as to provide an overlapping margin sufficient toprovide an intake filter of conical contour, with the apex of theconical configuration completely closed by reason of the bending of theflap 22 along the line 24. Thus a filter blank l0 cut in accordance withFigure 1 requires considerably less material than in a filter cut in theform of a disk. The saving in material amounts to the amount of overlapas represented by the blanks Ill and [6.

Figure 5 illustrates a different form of blank 26 wherein the flap 28 ischaracterized by a straight edge 30, which edge parallels and is spaceda short distance from the fold line 32 passing through the center 34about which the curved edge 36 is inscribed. The widest portion of theblank I0 is located at the line 38 passing through the center 34 and atright angles to the line 32.

In folding the blank 26, the blank is first folded back upon itselfalong the line 38, as in Figure 6, and the doubled flap 28 is thenfolded back upon the blank 26 along the line 32, as in Figure '7. Thefolded blank is then opened to the position of Figure 6, with the flap28 doubled against the outer face of the conical contour of the filter.The apex of the filter contour of Figure 8 is also completely closed byreason of the folded flap 28.

In all the forms, the flaps provide effective closures by reason of thefact that the filter is first placed in the funnel and then wetted andpressed against the walls of the funnel to provide a tight fit. Theoverlapping portions of the blank will adhere firmly one to the other.

In the blank of Figure 5, such a contour represents a saving of almostfifty percent of the paper required in filters of disk formation.

The blank of Figure 5 will produce the same number of filters in a stocksheet of given area, but the filter of Figure 1 produces more scrap. Theform of Figure 1 works better in the funnel and is easier to foldcorrectly. In addition to effecting a considerable saving in material,filters in accordance with my invention efiect a considerable saving inthe matter of packaging in that a considerably larger number of blanksmay be packaged in a container of given size. The waste clippings aresalvaged and employed for pulp and mass filters.

Without further elaboration, the foregoing will so fully illustrate myinvention, that others may, by applying current knowledge, readily adaptthe same for use under various conditions of service.

I claim:

A filter comprising a substantially semicircular shaped filter paperhaving a flange extending from the straight edge thereof, the flangegradually increasing in width in both directions from the center line ofthe sheet and flange, the sheet and flange being folded upon said line,and the flange being folded onto the folded sheet to provide the filterwhen opened with a closure flap gradually increasing in width in anupward direction.

JOHN M. SANFORD.

